JP2014039411A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly-reliable motor by suppressing generation of abnormal noise and suppressing a slide loss at a bearing part to a low level even when a drive load is large.SOLUTION: In a motor 1, a bearing mechanism 7 includes: a ball 76 fixed to an end part 52 of a rotary shaft 50; and a bearing member 70 having a recessed part 71 rotatably supporting the rotary shaft 50 via the ball 76. An endmost part (an end surface 520) in the motor axial line direction L located at a side closest to the bearing member 70, of the rotary shaft 50 is located on an opposite side to the bearing member 70 from the maximum diameter part of the ball 76. An inner peripheral side surface 73 of the recessed part 71 of the bearing member 70 is located at the radial outside of the maximum diameter part of the ball 76. As a result, even when the bearing mechanism 7 is configured by utilizing the ball 76, positional deviation between the rotary shaft 50 and the ball 76 is not generated. In addition, unlike in the case of performing working such as cutting and grinding on the end part of the rotary shaft 50 to form a bearing hemisphere part, a surface roughness of the ball 76 is small.

Description

  The present invention relates to a motor that rotatably supports a rotating shaft via a ball.

  In a drive device for an optical disc such as a DVD or a Blu-ray disc, a stepping motor is used to drive the optical head. In such a stepping motor, the outer surface of the rotor protruding from the stator on the rotating shaft of the rotor A spiral groove is formed to engage the rack. Further, a recess is formed on the end surface of the rotating shaft, and a ball is disposed between the recess and the bearing member. For this reason, the rotating shaft is rotatably supported by the bearing member via the ball. The ball is applied with a pressure in the axial direction of the rotating shaft directly or via a bearing member by an urging member such as a plate spring or a coil spring. It is designed to prevent the occurrence of rattling (see Patent Document 1).

  Also, instead of a bearing structure that rotatably supports the rotating shaft of the rotor via a ball, a structure in which the end of the rotating shaft is processed into a hemisphere and the hemispherical end is supported by a bearing member is practical. (See Patent Document 2).

JP-A-5-56622 JP 2007-104849 A

  In a motor in which a spiral groove is formed on the rotating shaft, when the rack is driven by engaging the spiral groove with the rack, an axial force is applied to the spiral groove. Further, when the surface roughness of the spiral groove is large and the frictional resistance is large, a force (side pressure) of a direction component orthogonal to the axial direction is applied to the rotation shaft via the spiral groove. At this time, if the load from the driven object is large, the rotating shaft is displaced in a direction orthogonal to the axial direction, and abnormal noise such as a hitting sound caused by collision between members is generated in the motor.

  Also, in recent years, optical head drive devices for Blu-ray compatible optical disks have increased in weight due to the increase in Blu-ray compatible components and the adoption of a metal chassis with high heat dissipation. When the side pressure increases, abnormal noise (striking sound) is likely to occur in the motor. Also, in a Blu-ray compatible optical head drive device or the like, conventionally, a solenoid is used for unlocking the disk loading device separately from the optical head drive motor, but the rotation of the optical head drive motor is not possible. A mechanism is used that unlocks the disk loading device. Even when such a configuration is adopted, since a large lateral pressure is applied to the rotating shaft, abnormal noise (striking sound) is likely to occur in the motor. The occurrence of such abnormal noise is not preferable because it causes noise in a device in which the motor is used and may lead to motor failure.

  In addition, when the bearing hemisphere part is formed by cutting or grinding the end of the rotating shaft as in the configuration described in Patent Document 2, the surface roughness of the hemisphere part is large. There is a problem that a large sliding loss is likely to occur between the bearing member and the bearing member. Further, when the surface roughness of the hemispherical portion is large, there is a problem in that wear tends to proceed on the bearing member side, resulting in a decrease in reliability.

  In view of the above problems, an object of the present invention is to provide a highly reliable motor by suppressing the generation of abnormal noise even when the driving load is large and by suppressing the sliding loss at the bearing portion. It is in.

  In order to solve the above-mentioned problems, in the present invention, a cylindrical stator and a rotor disposed on the inner side in the radial direction of the stator, the rotating shaft extending in the rotor from the stator. In a motor in which a spiral groove is formed on the outer peripheral surface of the protruding portion, a ball fixed to an end portion in the axial direction of the rotating shaft, and a movement restricting portion that restricts the movement of the ball in the radially outward direction. And a bearing member that rotatably supports the rotating shaft, and a biasing member that biases the ball toward the side where the rotating shaft is located.

  In the present invention, since the ball is fixed to the end portion of the rotating shaft, when a side pressure is applied to the rotating shaft when a bearing is configured using the ball, the movement of the ball in the radial direction is restricted by the movement restricting portion. However, no positional deviation occurs between the rotating shaft and the ball. Therefore, it is possible to prevent the generation of abnormal noise such as a hitting sound caused by the rattling between the rotating shaft and the ball. Further, the ball has a structure in which a ball formed separately from the rotation shaft is fixed to the rotation shaft. For this reason, the surface roughness of the ball is small, unlike the case where the end portion of the rotating shaft is subjected to processing such as cutting or grinding to form a hemispherical portion for a bearing. Therefore, a large sliding loss does not occur between the bearing member and the ball, the wear of the bearing member is small, and the reliability is improved.

  In this invention, it is preferable that the said ball | bowl and the said bearing member are provided in the edge part of the side in which the said stator of the said rotating shaft is located. When the motor rotates, a radial force is generated in the rotor, and this force may cause a positional shift between the ball and the rotating shaft. However, the present invention is provided at the end of the rotating shaft on the side where the stator is located. If the bearing structure which concerns on is employ | adopted, it can suppress that an abnormal noise generate | occur | produces at the time of rotation of a motor.

  In the present invention, in the axial direction, it is preferable that the outermost end portion of the rotating shaft that is positioned closest to the bearing member is positioned on the opposite side of the bearing member from the maximum diameter portion of the ball. According to such a configuration, since the movement restricting portion can be provided at a position close to the rotation axis, the movement restricting portion can be disposed outside the portion having a large ball diameter in the axial direction. For this reason, the sliding loss when the movement restricting portion and the ball come into contact with each other is small.

  In the present invention, the movement restricting portion is a wall surface extending in parallel with the axial direction so as to surround the ball outside the radial direction of the ball, and the movement restricting portion is in the axial direction. It is preferable to restrict the movement of the ball in the radial direction by contacting the maximum diameter portion of the ball from the outside in the radial direction. According to this configuration, the sliding loss between the bearing member and the ball is small. Also, when the ball is displaced in a direction perpendicular to the motor axial direction due to the influence of the lateral pressure applied to the rotating shaft, or due to the deterioration of the biasing member, the urging force in the motor axial direction on the bearing member decreases. Even in this case, the receiving portion of the bearing member is in contact with the maximum diameter portion of the ball from the outside in the radial direction to restrict movement. For this reason, since rattling between the bearing member and the ball is suppressed, it is possible to prevent the occurrence of abnormal noise caused by the rattling between the bearing member and the ball.

  In this invention, it is preferable that the surface roughness of the said ball | bowl is smaller than the surface roughness of the outer peripheral surface of the said rotating shaft. According to such a configuration, a large sliding loss does not occur between the bearing member and the ball, and the wear of the bearing is small and the reliability is improved.

  In the present invention, the end surface of the rotating shaft located on the bearing member side is formed with a recess that expands toward the bearing member, and the inner peripheral surface of the recess is in contact with the ball. preferable. According to such a configuration, since the position of the ball with respect to the rotating shaft is reliably defined in the axial direction, the outermost end portion of the rotating shaft is surely positioned on the side opposite to the bearing member from the maximum diameter portion of the ball. become. Accordingly, the movement restricting portion is supported by the bearing member in a stable state even when a side pressure is applied to the rotating shaft.

  In the present invention, it is possible to adopt a configuration in which the ball is fixed to the rotating shaft by adhesion. According to such a configuration, even when the material of the ball and the rotating shaft is different, the ball and the rotating shaft can be fixed.

  In this case, an annular gap sandwiched between the inner peripheral surface of the concave portion and the outer peripheral surface of the ball is formed on the bearing member side from the contact portion between the inner peripheral surface of the concave portion and the ball. Is preferred. According to this structure, it can suppress that an adhesive agent protrudes to the large diameter part of a ball | bowl.

  In the present invention, the ball may be configured to be fixed to the rotary shaft by welding.

  In this case, it is preferable that the rotating shaft is a small diameter portion in which the outer diameter dimension of the portion where the ball is welded is smaller than the portion located inside the stator. According to this configuration, it is easy to perform welding by irradiating the laser beam at the boundary between the end of the rotating shaft and the ball.

  In this invention, it is preferable that the said bearing member is provided with the receiving part which contacts the said ball | bowl in the said axial direction, and supports the said rotating shaft rotatably.

  In this invention, the said receiving part is comprised as a bottom part of the recessed part formed in the said bearing member, for example, and the said urging | biasing member urges | biases the said rotating shaft via the said bearing member.

  In this invention, it is preferable that the said ball | bowl and the said bearing member are provided in each of the both ends of the said axial direction of the said rotating shaft.

  In the present invention, since the ball is fixed to the end portion of the rotating shaft, when a side pressure is applied to the rotating shaft when a bearing is configured using the ball, the movement of the ball in the radial direction is restricted by the movement restricting portion. However, no positional deviation occurs between the rotating shaft and the ball. Therefore, it is possible to prevent the generation of abnormal noise such as a hitting sound caused by the rattling between the rotating shaft and the ball. Further, the ball has a structure in which a ball formed separately from the rotation shaft is fixed to the rotation shaft. For this reason, the surface roughness of the ball is small, unlike the case where the end portion of the rotating shaft is subjected to processing such as cutting or grinding to form a hemispherical portion for a bearing. Therefore, a large sliding loss does not occur between the bearing member and the ball, the wear of the bearing member is small, and the reliability is improved.

It is explanatory drawing of the motor which concerns on Embodiment 1 of this invention. It is explanatory drawing of the bearing structure of the non-output side of the motor which concerns on Embodiment 1 of this invention. It is explanatory drawing of the bearing structure of the non-output side of the motor which concerns on the example of improvement of Embodiment 1 of this invention. It is explanatory drawing of the bearing structure by the side of the non-output side of the motor which concerns on another improvement of Embodiment 1 of this invention. It is explanatory drawing of the bearing structure of the non-output side of the motor which concerns on Embodiment 2 of this invention.

  An example of a motor to which the present invention is applied will be described with reference to the drawings. In the following description, in the motor axial direction L, the side on which the rotating shaft 50 protrudes from the stator 40 is referred to as an output side L1, and the side opposite to the side on which the rotating shaft 50 protrudes from the stator 40 is the non-output side. This will be described as L2.

[Embodiment 1]
(overall structure)
FIG. 1 is an explanatory view of a motor according to Embodiment 1 of the present invention, and FIGS. 1A, 1B, and 1C are a half sectional view of the motor, a side view seen from the non-output side L2, FIG. 6 is an enlarged cross-sectional view showing an end portion of the non-output side L2.

  A motor 1 shown in FIG. 1 is a stepping motor used for driving an optical head in an optical disk driving device such as a DVD or a Blu-ray disc, and has a cylindrical stator 40 and a motor case 10 surrounding the stator 40. doing. The motor case 10 includes a first case member 11 that covers a portion located on the output side L1 of the stator 40, and a second case member 12 that covers a portion located on the counter-output side L2 of the stator 40.

  In the stator 40, an annular first bobbin 2 </ b> A and a second bobbin 2 </ b> B around which the coil 25 is wound are disposed so as to overlap in the motor axial direction L. An annular inner stator core 3A and an outer stator core 4A are disposed on both sides of the first bobbin 2A in the motor axial direction L, and an annular inner stator core 3B is disposed on both sides of the second bobbin 2B in the motor axial direction L. And the outer stator core 4B is arranged so as to overlap. On the inner peripheral surfaces of the first bobbin 2A and the second bobbin 2B, a plurality of pole teeth 31 and 41 of the inner stator cores 3A and 3B and the outer stator cores 4A and 4B are arranged in the circumferential direction. Thus, the cylindrical stator 40 provided with the rotor arrangement | positioning hole 30 is comprised, and the rotor 5 is coaxially arrange | positioned inside the stator 40 radial direction.

  In the rotor 5, the rotating shaft 50 extends in the motor axial direction L, and a cylindrical rotor magnet 59 is fixed to a position near the counter-output side L 2 of the rotating shaft 50. In this embodiment, the two rotor magnets 59 are provided at positions separated from each other in the motor axial direction L, and both of the two rotor magnets 59 are connected to the stator pole teeth 31 and 41 inside the rotor arrangement hole 30. Opposite through the interval. The rotating shaft 50 has a spiral groove 58 formed on the outer peripheral surface on the side protruding from the stator 40 (output side L1), and constitutes a rack-pinion mechanism together with a rack formed on the optical head (not shown) side. ing. At that time, since the rack is biased toward the spiral groove 58, a lateral pressure in a direction orthogonal to the motor axial direction is applied to the rotating shaft 50. Further, when the rack is driven, a force in the motor axial direction L is applied to the spiral groove 58. However, if the surface roughness of the spiral groove 58 is large and the frictional resistance is large, the frictional force causes the spiral shaft 58 to spiral. A force (side pressure) of a direction component perpendicular to the motor axial direction L is applied through the groove 58. Such a lateral pressure increases as the driving load of the driving target increases, such as the weight of the optical head is large. In the present embodiment, the motor 1 is used for unlocking the disk loading device by using the movement of the carriage engaged with the rotary shaft 50 in the optical disk driving device. The load is large. Therefore, in the motor 1 of this embodiment, a large lateral pressure is applied to the rotating shaft 50 from a direction orthogonal to the motor axial direction L.

  In the present embodiment, in the motor case 10, a plate 65 is fixed to the end surface of the first case member 11 on the output side L 1, and the distal end side bent portion 651 of the plate 65 is connected to the output side L 1 of the rotary shaft 50. A bearing mechanism 6 on the output side L1 that supports the end 51 so as to be rotatable in the motor axial direction L and the radial direction is configured. On the other hand, in the motor case 10, a cylindrical bearing holder 75 is fixed to the end surface of the second case member 12 on the opposite output side L2 by welding or the like. A bearing mechanism 7 on the counter-output side L2 is configured to support the end 52 on the counter-output side L2 of 50 so as to be rotatable in the motor axial direction L and the radial direction. In this embodiment, even when a lateral pressure is applied to the rotary shaft 50 from a direction orthogonal to the motor axial direction L, the following description will be given so that no abnormal noise due to rattling occurs in the bearing mechanisms 6 and 7. The structure to be adopted is adopted.

(Non-output side L2 bearing structure)
FIG. 2 is an explanatory diagram of the bearing mechanism 7 on the counter-output side L2 of the motor 1 according to the first embodiment of the present invention. FIGS. 2 (a) and 2 (b) are cross-sectional views of members constituting the bearing mechanism 7. FIG. It is a figure and sectional drawing of the bearing mechanism 7. FIG. In FIG. 2, the urging member is not shown.

  In FIG. 1 and FIG. 2, in the bearing mechanism 7 provided on the counter-output side L <b> 2 in the motor axial direction L, a disk-shaped bearing member 70 is supported inside the bearing holder 75, and the counter-output side of the rotary shaft 50 is The end portion 52 of L2 is supported by the bearing member 70 via a ball 76 interposed between the end portion 52 and the bearing member 70 so as to be rotatable in the motor axial direction L and the radial direction.

  The bearing member 70 is formed with a recess 71 that is recessed toward the counter-output side L2 at the end face of the output side L1, and a portion of the ball 76 that is positioned on the counter-output side L2 is fitted inside the recess 71. Yes. In this embodiment, the concave portion 71 is a bottomed concave portion having a bottom portion 72 (receiving portion) that rotatably supports the ball 76 from the opposite side in the motor axial direction L, and the bottom portion 72 is a conical surface. In the recess 71, an inner peripheral side surface 73 (wall surface) formed of a circumferential surface forms a straight hole having the same diameter and extending in the motor axial direction L, and the inner peripheral side surface 73 has a diameter of the ball 76. It surrounds the ball 76 outside in the direction. The inner diameter of the recess 71 is set to be slightly larger than the diameter of the ball 76, and the inner circumferential side surface 73 of the recess 71 restricts the movement of the ball 76 in the radial direction perpendicular to the motor axial direction L. It is configured as a part.

  A concave portion 521 that is recessed toward the output side L1 is formed on the end surface 520 that faces the bearing member 70 at the end 52 on the counter-output side L2 of the rotating shaft 50, and the portion that is located on the output side L1 of the ball 76 Is located inside the recess 521. In the present embodiment, the inner peripheral surface 522 of the recess 521 is a conical surface that increases in diameter toward the counter-output side L2 (the side on which the bearing member 70 is located).

  Here, the bearing member 70 is configured to be movable in the motor axial direction L inside the bearing holder 75, and the bearing member 70 has a leaf spring shape disposed on the opposite output side L <b> 2 with respect to the bearing member 70. The biasing member 77 biases the output L1 toward the output side L1. The urging member 77 includes an end plate portion 771 that overlaps the surface of the bearing member 70 on the non-output side L2, a pair of hook portions 772 that protrude from opposite sides of the end plate portion 771 toward the output side L1, The side plate portion 773 protrudes from the other side portion of the end plate portion 771 toward the output side L1. For this reason, the urging member 77 is fixed to the bearing holder 75 by the hook portion 772 passing through the side surface of the bearing holder 75 and catching on the end surface of the output side L1. At that time, the side plate portion 773 of the urging member 77 is positioned in contact with the side surface of the hook portion 772.

  A leaf spring portion 775 is cut and raised at the center portion of the end plate portion 771, and the leaf spring portion 775 biases the bearing member 70 toward the output side L1. For this reason, the ball 76 is urged toward the output side L1 (side on which the rotary shaft 50 is located) via the bearing member 70 by the leaf spring portion 775, and the output side L1 includes the output side of the rotary shaft 50. The bearing mechanism 6 on the output side L1 is configured to support the end portion 51 of the L1 so as to be rotatable in the motor axial direction L and the radial direction. Accordingly, since the rotary shaft 50 is biased so that the end portion 51 on the output side L1 contacts the bearing mechanism 6, when the rotary shaft 50 rotates, the rotary shaft 50 in the motor axial direction L is rotated. Shaking is prevented.

  In the bearing mechanism 7 configured as described above, the ball 76 is fixed to the end portion 52 of the rotating shaft 50. More specifically, the ball 76 is a sphere formed separately from the rotating shaft 50, and the ball 76 is an inner peripheral surface 522 of the recess 521 formed on the end surface 520 on the opposite output side L 2 of the rotating shaft 50. And an adhesive P applied so as to straddle the ball 76. For this reason, unlike the case where the end of the rotating shaft 50 is cut or ground to form a bearing hemisphere, the surface roughness of the surface sliding with the bearing member 70 (the ball 76) (Surface roughness) is small. More specifically, the surface roughness of the ball 76 is smaller than the surface roughness of the outer peripheral surface of the rotating shaft 50. Further, in this embodiment, since the ball 76 and the rotary shaft 50 are fixed by the adhesive P, the ball 76 and the rotary shaft 50 are securely connected even when the materials of the ball 76 and the rotary shaft 50 are different. Can be fixed. For example, even if the rotating shaft 50 is made of an iron-based metal such as stainless steel or brass and the ball 76 is made of ceramics, the ball 76 and the rotating shaft 50 can be reliably fixed. Moreover, even if both the ball 76 and the rotating shaft 50 are ferrous metals, the ball 76 and the rotating shaft 50 can be reliably fixed. In this embodiment, since grease or oil is applied to the bearing mechanism 7, an epoxy resin adhesive is used as the adhesive P so that the adhesive P is not deteriorated by the grease or oil.

  Here, the inner peripheral surface 522 of the recess 521 is a conical surface whose diameter increases toward the counter-output side L2 (the side on which the bearing mechanism 7 is located). In this embodiment, the center of the cone forming the recess 521 The angle θ formed by the line (virtual line extending perpendicularly from the apex of the cone to the bottom surface) and the generatrix (inner circumferential surface 522) is set to 30 °. In the present embodiment, the size of the opening of the recess 521 and the size of the ball 76 are such that the most end portion (end surface 520) located closest to the bearing member 70 of the rotating shaft 50 in the motor axial direction L is the ball 76. Is set so as to be positioned on the output side L1 opposite to the bearing member 70 from the maximum diameter portion (the position indicated by the alternate long and short dash line B). Therefore, even when the inner peripheral side surface 73 of the recess 71 is positioned radially outside the maximum diameter portion of the ball 76 (position indicated by the alternate long and short dash line B), it is positioned closest to the bearing member 70 of the rotary shaft 50. A sufficient gap G is secured in the motor axial direction L between the outermost end portion (end surface 520) and the surface 74 on the output side L1 of the bearing member 70.

(Bearing structure of output side L1)
In FIG. 1 again, the bearing mechanism 6 provided on the output side L1 in the motor axial direction L also employs the same configuration as the bearing mechanism 7. More specifically, the ball 66 is disposed between the bearing member 60 on the output side L1 held by the distal end side bent portion 651 of the plate 65 and the end portion 51 on the output side L1 of the rotating shaft 50. . Here, a concave portion 511 that is recessed toward the non-output side L2 is formed on the end surface 510 of the output side L1 of the rotating shaft 50, and the end surface of the bearing member 60 that is recessed toward the output side L1 is recessed toward the output side L1. A receiving portion 61 is formed, and a ball 66 is disposed between the concave portion 511 of the rotating shaft 50 and the receiving portion 61 of the bearing member 60. In the bearing mechanism 6, the ball 66 may have a structure that is not fixed to the rotating shaft 50. However, in this embodiment, as described with reference to FIG. Is fixed to the recess 511 of the rotating shaft 50 by an adhesive. Since the configuration of the bearing mechanism 6 is substantially the same as that of the bearing mechanism 7, the description thereof is omitted. The bearing member 60 has a large-diameter portion 64 that comes into contact with the surface on the counter-output side L2 of the distal-end bending portion 651 in a state of passing through a hole 652 formed in the distal-end bending portion 651 of the plate 65. Therefore, it is fixed to the distal end side bent portion 651.

(Main effects of this form)
As described above, in the motor 1 of this embodiment, the bearing mechanism 7 includes the ball 76 fixed to the end 52 of the rotating shaft 50 and the recess 71 that rotatably supports the rotating shaft 50 via the ball 76. Since the bearing member 70 is provided, even when the bearing mechanism 7 is configured using the ball 76, the positional deviation between the rotating shaft 50 and the ball 76 does not occur. Therefore, it is possible to prevent the generation of abnormal noise caused by rattling between the rotating shaft 50 and the ball 76. In addition, the rotary shaft 50 has a spiral groove 58 formed by a cutting process or a rolling method, and a barrel finish is performed after forming the recessed part 521 by the cutting process. Therefore, there is a dent or the like on the inner peripheral surface 522 of the recessed part 521. Although it is easy to generate | occur | produce, in this form, since the rotating shaft 50 and the ball | bowl 76 are being fixed, when the rotating shaft 50 rotates, it can prevent generating noise by presence of a dent.

  Further, since the ball 76 is formed separately from the rotating shaft 50 and is fixed to the rotating shaft 50, the end of the rotating shaft 50 is subjected to processing such as cutting and grinding to provide a bearing. Unlike the case where the hemispherical portion is formed, the surface roughness of the ball 76 is small. Therefore, a large sliding loss does not occur between the bearing member 70 and the ball 76, the wear of the bearing is small, and the reliability is improved.

  Further, in the motor axial direction L, the outermost end portion (end surface 520) located closest to the bearing member 70 of the rotary shaft 50 is located on the opposite side of the bearing member 70 from the maximum diameter portion of the ball 76. The inner peripheral side surface 73 (movement restricting portion) of the concave portion 71 formed in the above is located on the radially outer side of the maximum diameter portion of the ball 76. For this reason, even when a lateral pressure is applied to the rotating shaft 50 and the ball 76 is displaced in a direction perpendicular to the motor axial direction L, the ball 76 is displaced from the bottom 72 of the recess 71. 73 abuts. Therefore, since the rattling between the bearing member 70 and the ball 76 is suppressed, it is possible to prevent the generation of abnormal noise caused by the rattling between the bearing member 70 and the ball 76. Further, even when the ball 76 and the inner peripheral side surface 73 of the recess 71 come into contact with each other, the maximum diameter portion of the ball 76 slides on the inner peripheral side surface 73 of the recess 71. Small sliding loss. Even when the urging force in the motor axial direction L with respect to the bearing member 70 is reduced due to the deterioration of the plate spring portion 775 of the urging member 77, the inner peripheral side surface 73 of the recess 71 formed in the bearing member 70 is reduced. It abuts on the maximum diameter portion of the ball 76 from the outside in the radial direction. For this reason, since the rattling between the bearing member 70 and the ball 76 is suppressed, it is possible to prevent the generation of noise due to the rattling between the bearing member 70 and the ball 76.

[Improvement of Embodiment 1]
FIG. 3 is an explanatory diagram of the bearing mechanism 7 on the counter-output side L2 of the motor 1 according to the improvement example of the first embodiment of the present invention. FIGS. 1 is a cross-sectional view of a bearing mechanism 7 according to FIG.

  In the first embodiment, at the end 52 of the rotation shaft 50, the center line (virtual line extending perpendicularly from the apex of the cone to the bottom surface) of the cone constituting the recess 521, the generatrix of the cone (inner peripheral surface 522), Was set to 30 °. On the other hand, in the improved example 1 shown in FIG. 3A, the center line (virtual line extending perpendicularly from the apex of the cone to the bottom surface) of the cone constituting the recess 521 and the conical bus (inner peripheral surface 522). 3) is set to 45 °, and in the improved example 2 shown in FIG. 3B, the center line of the cone constituting the recess 521 (virtual line extending perpendicularly from the apex of the cone to the bottom surface), The angle θ formed by the conical bus (inner peripheral surface 522) is set to 60 °.

  According to this configuration, the position where the inner peripheral surface 522 of the recess 521 and the ball 76 are in contact is located on the output side L1 as compared to the first embodiment. For this reason, as shown in FIG. 3 (c), there is sufficient space between the outermost end portion (end surface 520) located closest to the bearing member 70 of the rotating shaft 50 and the surface 74 of the output side L 1 of the bearing member 70. Even when the gap G is secured, the annular member sandwiched between the inner peripheral surface 522 of the recess 521 and the outer peripheral surface of the ball 76 is located closer to the bearing member 70 than the contact portion between the inner peripheral surface 522 of the recess 521 and the ball 76. The gap 78 can be secured. Accordingly, since the adhesive P is held in the gap 78, the adhesive P does not reach the position where the bearing member 70 and the ball 76 are in contact (the maximum diameter portion of the ball 76 / the position indicated by the alternate long and short dash line B). . Therefore, no sliding loss or the like due to the adhesive P occurs between the bearing member 70 and the ball 76. In particular, when the adhesive P is applied after the ball 76 is pressed and temporarily fixed to the concave portion 521 of the rotating shaft 50, the applied adhesive P is applied to the annular gap 78 by the capillary force. Go around the whole. Therefore, the rotating shaft 50 and the ball 76 can be securely fixed.

[Another improvement of the first embodiment]
FIG. 4 is an explanatory diagram of the bearing mechanism 7 on the non-output side L2 of the motor 1 according to another modification of the first embodiment of the present invention.

  As shown in FIG. 4, when the inner peripheral surface 522 of the recess 521 of the rotating shaft 50 and the ball 76 are fixed by the adhesive P, the outermost end portion (end surface 520) located closest to the bearing member 70 of the rotating shaft 50. Notches 525 are formed at equal angular intervals at a plurality of locations in the circumferential direction toward the output side L 1, and bonded between the inner peripheral surface 522 of the recess 521 of the rotating shaft 50 and the ball 76 inside the notch 525. The agent P may be applied. According to this configuration, the adhesive strength between the rotating shaft 50 and the ball 76 can be increased, and even if the adhesive strength is increased, the position where the bearing member 70 and the ball 76 are in contact with each other on the output side L1 (the maximum of the ball 76). The adhesive P does not reach the diameter portion / the position indicated by the alternate long and short dash line B).

[Embodiment 2]
FIG. 5 is an explanatory diagram of the bearing mechanism 7 on the counter-output side L2 of the motor 1 according to the second embodiment of the present invention. FIGS. 5 (a), 5 (b), and 5 (c) each form a recess 521. It is sectional drawing at the time of setting the angle (theta) which the centerline in the cone and the generatrix of a cone make to 30 degrees, 45 degrees, and 60 degrees.

  In the first embodiment, the rotating shaft 50 and the ball 76 are fixed by an adhesive. However, in this embodiment, as shown in FIG. 5, the endmost portion (end surface 520) of the rotating shaft 50 located closest to the bearing member 70 is used. ) Is irradiated with the laser beam S, and the end 52 of the rotating shaft 50 and the ball 76 are fixed by welding. That is, in this embodiment, the rotating shaft 50 is a stainless material such as SUS303 or SUS410, the ball 76 is a bearing steel such as SUJ2, and both the rotating shaft 50 and the ball 76 are an iron-based material. For this reason, in this embodiment, laser light is irradiated to two circumferential positions of the boundary between the end 52 of the rotating shaft 50 and the ball 76, and the end 52 of the rotating shaft 50 and the ball 76 are fixed by welding. It is. More specifically, after pressing the ball 76 against the concave portion 521 of the rotating shaft 50 and temporarily fixing it, the laser beam is irradiated from a direction perpendicular to the motor axial direction L.

  Here, in the example shown in FIG. 5A, a center line (virtual line extending perpendicularly from the apex of the cone to the bottom surface) of the cone constituting the recess 521 and a cone generating line (inner peripheral surface 522) are formed. The angle θ is set to 30 °, the angle θ is set to 45 ° in the example shown in FIG. 5B, and the angle θ is set to 60 ° in the example shown in FIG. As can be seen by comparing these forms, the larger the angle θ is, the more the welded part is located away from the bearing member 70. For this reason, the welding mark does not reach the position where the bearing member 70 and the ball 76 are in contact (the maximum diameter portion of the ball 76 / the position indicated by the alternate long and short dash line B). There is no sliding loss due to welding marks.

  In this embodiment, the rotary shaft 50 is a small-diameter portion 528 having an outer diameter smaller than that of the portion where the end 52 is located inside the stator 40 (see FIG. 1). The outer diameter dimension at is only slightly larger than the diameter of the ball 76. Therefore, it is easy to irradiate the laser beam to the boundary between the end portion 52 of the rotating shaft 50 and the ball 76 for welding. Even when a welding mark generated during welding of the end portion 52 of the rotating shaft 50 and the ball 76 rises outward in the radial direction of the rotating shaft 50, the end portion 52 is a small diameter portion 528. Thereafter, there is no problem in passing the magnet 59 shown in FIG.

[Other embodiments]
In the first and second embodiments, the urging member 77 urges the ball 76 via the bearing member 70. However, the recess 71 of the bearing member 70 is a through hole, and the urging member 77 is a ball. You may apply this invention to the motor 1 of the structure which urges | biases 76 directly.

  In the first and second embodiments, the inner peripheral side surface 73 of the recess 71 is used as a movement restricting portion that restricts the movement of the ball 76 in the radial direction, and the bottom portion 72 formed of a conical surface is used for the ball 76 in the motor axial direction L. Although the receiving portion is supported, the conical surface formed in the recess 71 is used as a movement restricting portion that restricts the radial movement of the ball 76 and is also used as a receiving portion that supports the ball 76 in the motor axial direction L. Also good. In addition, the movement restricting portion that restricts the movement of the ball 76 in the radial direction and the receiving portion that supports the ball 76 in the motor axial direction L may be configured by separate members. The ball 76 is urged through the member in which the receiving portion is formed. Furthermore, the bottom 72 of the recess 71 of the bearing member 70 is not limited to a conical shape, and may be a pyramid shape. Furthermore, the bottom 72 of the recess 71 of the bearing member 70 is not limited to a conical shape or a pyramid shape, and may be a flat surface. In this case, the bottom 72 of the bearing member 70 functions as a thrust bearing, and the inner peripheral side surface 53 of the recess 71 of the bearing member 70 functions as a radial bearing.

  In the first and second embodiments, since the inner peripheral surface 522 of the concave portion 521 is a conical surface, the center line (virtual line extending perpendicularly from the apex of the cone to the bottom surface) of the cone constituting the concave portion 521 and the cone The angle θ formed by the bus (inner peripheral surface 522) is set to 45 ° or 60 ° larger than 30 ° so that the position where the inner peripheral surface 522 of the recess 521 contacts the ball 76 is positioned on the output side L1. However, when the concave portion 521 has an arc shape in cross section, the arc may be shallow so that the position where the inner peripheral surface 522 of the concave portion 521 and the ball 76 are in contact with each other is located on the output side L1.

  In the first embodiment, the ball 76 and the rotary shaft 50 are bonded by the adhesive P, but may be bonded by brazing.

  Of course, the present invention can be applied to motors other than stepping motors.

DESCRIPTION OF SYMBOLS 1 Motor 5 Rotor 6 Output side bearing mechanism 7 Counter output side bearing mechanism 40 Stator 50 Rotating shaft 51 Rotating shaft output side end 52 Rotating shaft opposite output side end 59 Rotor magnet 65 Plate 70 Bearing member 71 Recess 72 The bottom of the recess (receiving part)
73 Inner side surface of recess (movement restricting part)
75 Bearing holder 76 Ball 77 Biasing member 520 End face 521 on the opposite side of the rotating shaft Recess 522 Recess 522 Inner circumferential surface 775 Leaf spring

Claims (13)

A helical stator is formed on the outer peripheral surface of a portion of the rotating shaft that extends from the stator and that protrudes from the stator. Motor
A ball fixed to an axial end of the rotating shaft;
A bearing member that includes a movement restricting portion that restricts movement of the ball to the outside in the radial direction, and rotatably supports the rotating shaft;
A biasing member that biases the ball toward the side on which the rotation shaft is located;
The motor characterized by having.   The motor according to claim 1, wherein the ball and the bearing member are provided at an end of the rotating shaft on a side where the stator is located.   The endmost portion of the rotating shaft located closest to the bearing member in the axial direction is located on the side opposite to the bearing member from the largest diameter portion of the ball. 2. The motor according to 2. The movement restricting portion is a wall surface extending in parallel to the axial direction so as to surround the ball outside the radial direction of the ball,
4. The motor according to claim 3, wherein the movement restricting portion restricts the movement of the ball in the radial direction by contacting the maximum diameter portion of the ball in the axial direction from the outside in the radial direction. .   The motor according to any one of claims 1 to 4, wherein the surface roughness of the ball is smaller than the surface roughness of the outer peripheral surface of the rotating shaft. On the end surface located on the bearing member side of the rotating shaft, a concave portion is formed that expands toward the bearing member side,
The motor according to claim 1, wherein an inner peripheral surface of the recess is in contact with the ball.   The motor according to claim 6, wherein the ball is fixed to the rotating shaft by bonding.   An annular gap sandwiched between the inner peripheral surface of the concave portion and the outer peripheral surface of the ball is formed on the bearing member side from the contact portion between the inner peripheral surface of the concave portion and the ball. The motor according to claim 7.   The motor according to claim 6, wherein the ball is fixed to the rotating shaft by welding.   10. The motor according to claim 9, wherein the rotation shaft has a small diameter portion in which an outer diameter of a portion where the ball is welded is smaller than a portion located inside the stator.   The motor according to claim 1, wherein the bearing member includes a receiving portion that abuts on the ball in the axial direction and rotatably supports the rotating shaft. The receiving portion is a bottom portion of a recess formed in the bearing member,
The motor according to claim 11, wherein the biasing member biases the rotating shaft via the bearing member.   The motor according to any one of claims 1 to 12, wherein the ball and the bearing member are provided at both ends of the rotating shaft in the axial direction.

Images